The move was made as a response to the missile launch by North Korea into the Sea of Japan on 27th July. It hadn't previously announced the change.

An official at the Ministry of Land, Infrastructure and Transport said, "It appears that Singapore Airlines is flying over Busan and the east coast of Japan rather than flying through Gangwon Province and the East Sea".

USA officials toldCNN that the re-entry vehicle likely failed during North Korea's most recent missile test, and the crew of a Cathay Pacific flight claims to have seen the missile explode during re-entry, although David Wright, a senior physicist with the Union of Concerned Scientists, suspects that the crew actually saw stage separation and second-stage ignition during the ascent. Cathay Pacific's crew reported seeing the weapon re-enter the Earth's atmosphere, while Korean Air said its pilots "saw a flash".

While Singapore Airlines have continued to avoid the area, a flight crew on a different airline last Wednesday reported seeing North Korea's latest ICBM launch.

Pyongyang reported that its latest missile flew as high as 2,800 miles. "We remain alert and [will] review the situation as it evolves".

European airlines Lufthansa and Air France-KLM shifted their paths in August after two North Korean test launches in July.

At the time, U.S. Defense Department spokesman Jeff Davis warned that the missile North Korea "flew through busy airspace used by commercial airliners".

Under the guidelines of the International Civil Aviation Organization-a United Nations agency that oversees air safety-nations launching threats to air safety must "issue risk advisories regarding any threats to the safety of civilian aircraft operating in their airspace".